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US · United States · –

Cow Valley Fire, July 2024 Malheur

Out · last detection 20 Jul 2024, 21:12 UTC

The fire started on 11 July 2024 in Malheur, United States, and satellites saw it burning for 10 days. United States agencies (MTBS / NIFC) mapped an official burnt perimeter of 54,449 hectares, spread across a single county.

It is the 15th largest in Oregon since 2016 (of 325 with a page). Number 11 in United States in 2024, of 371.

Burnt area
54,449ha
official perimeter (MTBS / NIFC)
Duration
≈ 10days
11 Jul 2024 – 20 Jul 2024
Counties hit
1
counties
Started on
11 Jul
2024
Heat detections
2,044
in a single hotspot: 532 MW
Danger at start
55
Extreme · FWI index
Average daily power
8.7GW
detected power per day, on average

Where it burned

HOTSPOTS BY DAY 11 Jul20 Jul
20 Jul 2024

How it evolved, day by day

11 Jul 2024 · 12,602 MW · 134 12 Jul 2024 · 14,843 MW · 854 13 Jul 2024 · 9,071 MW · 685 15 Jul 2024 · 91 MW · 14 20 Jul 2024 · 6,770 MW · 357
11 Jul 12 Jul 13 Jul 15 Jul 20 Jul

Fire radiative power detected each day, in megawatts, and number of hotspots. The magenta bar marks the peak day.

The weather it burned in

38°high
55km/h · peak gust
5%lowest humidity

It had gone 23 days without rain (1 mm or more) when it started. Rain came after the fire: 1.2 mm on 22 Jul.

This area had burned before

No earlier perimeters overlap this fire since 2016, when the satellite record begins.

How big is it?

10 km
It burned the equivalent of 34% of the area of London (544 km² against 1,583 km²).

London boundary: geoBoundaries · Office for National Statistics (Open Government Licence v3.0).

This compares size, not location: both shapes are at the same scale, north up, centred on each other.

What happened to each county

  1. Malheur where it started
    55,372 ha reached on 11 Jul
    2.2 %

Burnt area inside each county, from crossing the official perimeter with administrative boundaries. The distance runs from the point marking the centre of each area to the nearest fire: staying a kilometre away does not mean it reached the houses.

People and buildings inside the perimeter

GHSL 2025
Built-up area0.39 ha
Residents< 20

Inside the perimeter there were about 0.39 hectares of built-up land and almost nobody lived there (GHSL 2025, satellite-based estimate).

This is an estimate on 100 m cells, made from satellite imagery and census data: it does not mean that homes burned or that anyone was harmed. The perimeter also contains land that never burned. The GHSL 2025 epoch is a projection made from 2020 and earlier data.

Source: Global Human Settlement Layer (GHS-BUILT-S and GHS-POP R2023A), European Commission Joint Research Centre (JRC), © European Union, CC BY 4.0. Sum inside the perimeter computed by WorldFires. human-settlement.emergency.copernicus.eu

The weather day by day

ECMWF ERA5 reanalysis at the fire location, the standard reference for past weather, and the Canadian Fire Weather Index (the same system Copernicus uses), computed by WorldFires from that data. Days after the fire run until the first rain.

Open-Meteo.com (CC BY 4.0) · Copernicus Climate Change Service (ERA5)

Started with Extreme FWI: 36 % of the area in United States Very dry air: 40 % of the area in United States

Day High Min. humidity Peak gust Rain Danger (FWI)
11 Jul 38.0 °C 9 % 46 km/h 0.0 mm Extreme 55
12 Jul 38.2 °C 7 % 41 km/h 0.2 mm Extreme 51
13 Jul 38.5 °C 5 % 30 km/h 0.1 mm Extreme 57
14 Jul 31.7 °C 17 % 55 km/h 0.0 mm Extreme 56
15 Jul 34.9 °C 9 % 38 km/h 0.0 mm Extreme 59
16 Jul 35.9 °C 7 % 24 km/h 0.0 mm Extreme 50
17 Jul 33.8 °C 12 % 41 km/h 0.0 mm Very extreme 71
18 Jul 36.6 °C 9 % 31 km/h 0.0 mm Very high 49
19 Jul 36.7 °C 11 % 48 km/h 0.0 mm Extreme 57
20 Jul 37.8 °C 10 % 41 km/h 0.0 mm Extreme 53
21 Jul after 35.9 °C 9 % 32 km/h 0.0 mm Extreme 61
22 Jul after 37.7 °C 13 % 41 km/h 1.2 mm Extreme 59

Its twins: fires that started in the same weather

It started with an FWI of 55.0, a minimum humidity of 9% and 23 days without rain. Fires in the area that started in weather like this since 2016: 19.

FWI at the start 55.0
Minimum humidity 9 %
Days without rain 23
this fire chosen twins rest of the area
Almost identicalSimilar

Outlines of the closest twins

Simmons Gulch Fire, August 2016
4,636 ha 3 days FWI 55.0 Min. humidity 8 % 51 km away, in 2016

First rain (1 mm or more) after it ended: none in the following ten days.

What happened to them

3 days
median duration
2,052 ha
median area
68 %
went past 1,000 ha
1.8 mm
rain at the end (median; 7 of 19 had it)

It was 26.5 times larger than the median of its twins and lasted 10 days, against 3 days.

None of its 19 twins burned more. The weather on the first day does not explain everything: the wind in the following days, the fuel and the firefighting also count. In 12 of 19, not even 1 mm fell in the ten days after the end: they went out without rain. In the rest, the first rainy day brought a median of 1.8 mm.

This is a bank of analogues: it shows what usually happens, not what will happen. With fewer than 15 twins we give no figures. How we calculate it

How it ended

1.2 mmfirst rain
22 Jul2 days after it ended
55km/h · max. gust

It was considered over on 20 Jul, and on 22 Jul 1.2 mm fell. We do not know whether the rain or the firefighters put it out. Twins with rain when they ended: 7 of 19, with a median of 1.8 mm.

Weather on this page: Open-Meteo.com (CC BY 4.0) · Copernicus Climate Change Service (ERA5)

How a twin is chosen

  • Same area: fires that have already ended, less than 250 km from this one, since 2016.
  • Same start: we compare the FWI on the first day, the minimum humidity that day and the run of days without rain before it. The slider sets how much they may differ.
  • Only pages with final weather data (ERA5 reanalysis) calculated in the same way as this fire’s; agricultural and grass burns and pages with data under review are left out.
  • Fires burning at the same time as this one (a week before or after) are left out: they share the same spell of weather and do not count as a precedent.
  • They are sorted by similarity, and the outlines of the first five are drawn.

How we calculate it

Before and after, from space

Drag the line to compare the same ground before the fire and after it.

Before · 4 Jul 2024
After · 27 Jul 2024

If the day is cloudy, change the date: each satellite passes once a day. In false colour the burnt ground looks brown or red.

The smoke

CAMS · Copernicus

On 13 July 2024 the air beside the fire reached 78 µg/m³ of PM2.5. That day averaged 36: 2.4 times the WHO daily guideline (15).

PM2.5 peak78 µg/m³
Days over the guideline2 days
PM10112 µg/m³
Optical depth1.38
9 Jul11 Jul13 Jul
Good Fair Moderate Poor Very poor Extremely poor

Particles from the Copernicus CAMS model at the centre of the perimeter; these are not measurements in each town. The pale bar is the worst hour, the solid one the daily average.

Open-Meteo.com (CC BY 4.0) · Copernicus Atmosphere Monitoring Service (CAMS)

Detections table · 2,044Every satellite heat detection, one by one, with time, satellite, power and coordinates.
⬇ Download CSV Times in UTC. Each detection is a 375 m pixel: a large fire yields hundreds per pass.
Date and timeSatelliteFRP (MW)LatLon

Other fires nearby

All fires in United States

Frequently asked questions

How long did the Cow Valley Fire last?
The official perimeter only gives the start date (11 July 2024). The end comes from the heat detections inside the perimeter: it burned until 20 July 2024 (10 days from 11 July 2024), the last day with detections before more than 10 days in a row without any, so it is approximate.
How much area did it burn?
The official perimeter published by United States agencies (MTBS / NIFC) is 54,449 hectares (544.5 km²). Other tallies, such as daily incident reports, may give slightly different figures.
Which counties burned?
The fire only entered Malheur (55,372 ha, 2.2 %).
What was the weather like?
During the fire the temperature reached 38.5 °C, humidity dropped to 5 % and gusts hit 55 km/h. The fire danger index (FWI) reached 71, class Very extreme.
Where does this data come from?
From the official burnt perimeter of United States agencies (MTBS / NIFC, public domain), NASA FIRMS VIIRS hotspots and the administrative boundaries of United States. It is not an official report.
How did the fires that started in similar weather in this area end?
Fires less than 250 km away that started since 2016 with a similar FWI, humidity and dry spell: 19. Their median duration was 3 days and their median area 2,052 ha; 68 % went past 1,000 ha. None of its 19 twins burned more. The weather on the first day does not explain everything: the wind in the following days, the fuel and the firefighting also count. In 12 of 19, not even 1 mm fell in the ten days after the end: they went out without rain. In the rest, the first rainy day brought a median of 1.8 mm.

Where to verify it

A satellite detection is not an official report. Final figures and the fire’s status are published by each country’s emergency service.

Emergency number: 911 · Emergency number and official warnings

Satellite cross-check

History of this page Changes in area, dates, name, official record or merged pages, compared every night since 24 October 2026.

Does something look wrong on this page?

This page is built from satellite data and official records, and it sometimes gets things wrong: the wrong dates, the wrong town, two fires merged into one, or something that was not a wildfire at all. If you know this fire first-hand (you live nearby, saw it, fought it or reported on it), tell us what really happened and we will check it.

Report an error
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We will only use your email to reply about this report. Privacy. This is not an emergency service: if there is a fire now, call 911.

How we know this
  • Perimeter: MTBS (US Geological Survey and US Forest Service), official.
  • The official perimeter has no end date: the end is the last day with VIIRS detections inside the perimeter before a gap of more than 10 days (150 days at most), so it is approximate. 2,044 Suomi-NPP VIIRS detections on those dates.
  • We have not matched this page with any official record.
  • Weather: Copernicus ERA5 reanalysis at the fire location, in cells of about 25 km.
  • Built-up area and population come from the JRC Global Human Settlement Layer (epoch 2025, 100 m cells), summed inside the perimeter: an estimate of what was there, not a damage count.

How we build fire pages: methodology

Where this data comes from

The perimeter is official and in the public domain. For past years it comes from MTBS (Monitoring Trends in Burn Severity), run by the U.S. Geological Survey and the USDA Forest Service, which map it on Landsat and Sentinel-2 imagery. For the current and last year it comes from WFIGS at the National Interagency Fire Center (NIFC): incident perimeters mapped by fire crews, aircraft and imagery. Heat detections come from the VIIRS sensors aboard Suomi-NPP and NOAA-20, distributed by NASA FIRMS at 375 m resolution. County boundaries come from geoBoundaries ADM2 (Public Domain). The area per county is computed by WorldFires by crossing the perimeter with those boundaries, so it may differ slightly from official figures.